The striker had been at Brackley Town, whom he joined in 2008 from Leamington FC, where he helped the Brakes to a couple of promotions with 57 goals in 95 starts.
Speaking about Mackey, who teams up with former Sky Blues Andy Gooding and Andy Hall, Corby boss Graham Drury said: Drury said: "Ben has been someone I have wanted to sign for a long time and at last it has come about. I think he will be great with Steve Diggin and is a prolific scorer himself.
"We still need one further striker and I have that person in mind but we have still to agree terms. "Whatever happens I am a happy man tonight having finally got Ben to join us."
Another former City youngster David Blenkinsopp has joined Sutton Coldfield Town. "Casper" as he was known during his time at Coventry City, where he played for the U18's and City Reserves, has also played for Rugby Town, Nuneaton Town, Halesowen Town and Gresley Rovers.